Telephone communication carriers, such as MCI, offer a host of enhanced voice services (EVS) for virtual phone numbers, such as 800 and 900 numbers. Typically, these services enable interactive communication between the caller and the carrier network. Voice services typically involve audio prompting of the caller which narrows down where the call will be routed. For example. a large corporation may involve extensive sales and service phone contacts at disparate geographical locations. By utilizing EVS, the caller may narrow the choice as to where his call should be routed. Responses from the caller are typically phone key entries (DTMF) or voice responses. The heart of the EVS network platform is an audio response unit (ARU) that provides specified voice prompts, that are stored on large hard drives, and typically customized for particular 800 or 900 number network customers.
An EVS system, as currently employed in the MCI network, is illustrated in FIG. 1 (prior art). In a typical scenario, a caller at phone 10 places an 800 number call which is routed, via link 12, to an MCI switch 14. The switch queries (along link 16), an available data access point (DAP) 18 which determines further routing of the call, based upon the 800 number dialed by the caller.
Once the routing for a call has been determnined to be for EVS, it is passed through the appropriate MCI switches 36 to the designated audio response unit (ARU) node 32,34. As will be observed in FIG. 1, each of the ARUs is connected with a respective switch 36, 38 and interconnected lines 40, 42, 44 and 46 that are connected as redundant pairs. Thus, if a particular ARU becomes seriously degraded, the audio response tasks may be switched to the other ARU in the pair from either switch. Each ARU includes a processor loaded with the same application scripts that define, by the initial incoming 800 number called and the DAP lookup, which audio files stored at the ARU are to be activated so as to complete a predefined interactive process with the caller.
From a call routing standpoint, failure of an ARU causes two things to happen: First, the EVS switch of the faulty ARU reroutes all incoming traffic to the partner ARU via a cross link 44, 46. Second, the EVS Audio Management System (AMS) 26 detects that an ARU is down and sends a failover message to the Data Access Point (DAP) to reroute any further calls to the faulty ARU's partner. This second mechanism results in reroutes at the initial DAP lookup.
The failover message from the AMS is sent to the DAP via the Service Control Manager (SCM) 22. However, each ARU can still not be allowed to run much higher than 50% of capacity under the current architecture in case it must suddenly receive calls originally intended for its failed partner.